Management efforts for the Lake Victoria Basin have been hampered by a lack of clear standards against which to judge the degree of environmental degradation, highlighting the need for a multi-metric approach for this purpose. Indeed, management priorities for the Lake Victoria catchment must be based on reliable assessments of the biological integrity of the inflowing rivers that can potentially influence the ecological functioning of the lake. Accordingly, macroinvertebrate metrics were evaluated for their responsiveness to human impacts, utilizing Pearson's correlations with physico-chemical parameters. The resultant 9 metrics that provided the best discrimination between physico-chemical samples, using the separation power of Mann-Whitney U and Kolmogorov-Smirnov tests (P < 0.05) from the 21 sampling sites utilized in this study were the: (i) abundances of Ephemeroptera, Plecoptera and Trichoptera; (ii) relative abundances of Diptera; (iii) Ephemeroptera, Plecoptera and Trichoptera:Diptera ratio; (iv) Oligochaeta, Mollusca, Hemiptera, Odonata and the proportions of tolerance taxa; (v) dominant taxa; and (vi) the relative proportions of invertebrates that fall into the gatherer and predator feeding groups, based on the variability they exhibited across the sampling sites. Using the inter-quartile ranges to establish the scoring criteria, the index was able to delineate impacted from less-impacted sites along the rivers, providing preliminary evidence of responses to changes in the ecosystem integrity exhibited by resident macroinvertebrate assemblages in both rivers.

This study examined the efficacy of community‐level fishery co‐management organizations called Beach Management Units (BMUs) along the Kenyan shores of Lake Victoria. BMUs were established to enhance sustainable Lake Victoria fishery management through increasing the level of community participation to assist in the administration of fisheries rules and regulations by, and for, the fishers. Inefficiencies have emerged, however, inhibiting the effective execution of sustainable fisheries management by the BMUs. Data were collected from 36 BMUs along the Kenyan shores of Lake Victoria. Descriptive and inferential analyses were performed using SPSS Version 20.0. The results indicated that BMUs are successful at educating fishers and that they are aware of fishing rules and regulations. Nevertheless, high violation rates were also observed, suggesting BMUs have limited impact on fisher decisions to comply with regulations. Data suggest that the failure to comply may be due to lack of adequate financial and equipment resources for monitoring, control and surveillance (MCS) operations, making them unable to control illegal fishing in their areas of jurisdiction. Furthermore, financial mechanisms, which would allow BMUs to sustainably fund their administrative and MCS operations, are weak, thereby reducing the BMUs ability to effectively function. The data from this study highlight two activities illustrating significant indices of good performance, namely resolving disputes and receiving visitors. The data also suggest the creation of BMUs has not ensured successful implementation of co‐management of Lake Victoria fisheries. BMUs are successful at activities of a social nature, but have poorly undertaken their core functions related to enforcement and compliance with fishing rules.

The water quality of many streams in Lake Victoria Basin, Kenya is affected by agricultural intensification, municipal and industrial effluent, as well as water abstraction, livestock and deforestation. Management efforts have been hampered by lack of clear standards against which to judge the degree of environmental degradation. To achieve this goal, a macroinvertebrate-based Index of Biotic Integrity was developed to monitor ecological integrity of selected rivers occurring in the same ecological zone in the upper reaches of the basin. Macroinvertebrates were sampled with a Surber sampler at 22 stations. The stations were grouped into three condition categories (reference, intermediate and impaired stations) according to the level of degradation. Twenty metrics representing the structural and functional organization of macroinvertebrates were computed using Mann-Whitney U tests. The separation power of the metrics was evaluated using box plots. Final metrics were evaluated for responsiveness by Pearson’s correlations with physicochemical parameters. Of the 20 metrics, 9 met the test criteria, as they displayed variability across the stations, and were used to provide the final scores for Macroinvertebrate Index of Biotic Integrity (M-IBI). Metric values at both reference and impaired sites were used to establish the scoring criteria using inter-quartile ranges. This index provided preliminary evidence of response to changes in ecosystem integrity exhibited by resident macroinvertebtrate assemblages in rivers in the upper reaches of Lake Victoria Basin. It was recommended that the index developed be used to assess and monitor rivers in the upper catchments of Lake Victoria Basin in Kenya.

The long term monitoring of aquatic ecosystems based on chemical analysis is expensive resulting in a lack of time series data for management purposes thus necessitating the need for new cost effective methodologies. This study developed a fish-based index of biotic integrity (FIBI) for monitoring environmental conditions in riverine ecosystems within the Lake Victoria Basin, Kenya. The fish fauna in the basin is poorly studied, less diverse and ecologically specialized than the temperate fauna that provided the origins of the Index of Biotic Integrity. Fish samples were collected by electrofishing from 24 sites during baseflow periods in February, March and July 2004. Validation data were collected from 7 sites with varying levels of degradation. Fish samples were identified, counted and grouped into different trophic groups, relative tolerance to pollution, habitat guild and whether exotic or native to riverine environment. Thirty-three candidate metrics were evaluated for responsiveness to habitat quality and twelve were selected for inclusion in the final index. The index classified 6 of the 7 validation sites according to their levels of degradation. As a bioassessment tool, the index was useful in laying the basis for long-term monitoring of rivers in the Lake Victoria drainage basin.

This study established for the first time the impact of harvesting on post-harvest papyrus (Cyperus papyrus L.) biomass regeneration potential, with two harvesting regimes compared. Aboveground papyrus biomass was determined. Biomass varied with site. Site had no effect on regeneration potential, but monthly harvesting reduced papyrus biomass regeneration potential among sites. However, seasonal (6-monthly) harvesting did not appear to affect papyrus biomass regeneration potential. Exponential and polynomial trend analyses revealed a consistent downward trend for monthly harvest biomass, and the polynomial trend was more linear (F = 97.913; P \ 0.001) than periodic (F = 9.617; P \ 0.05). The polynomial trend scenario indicated how papyrus biological dynamics are likely to behave as monthly harvests are repeated. This suggests that regeneration potential is significantly reduced with successive monthly harvest, leading to weak spatial connectivity, papyrus stand fragmentation, and increased landscape patchiness. A 6-month harvest regime can be established to regenerate more biomass between harvests than is currently the case, with positive implications for wetland conservation and carbon sequestration. Papyrus harvesters can be kept off the swamps by establishing a riparian buffer zone of agro forestry trees and shrubs which can substitute for the papyrus as it is left to mature. However, while the information presented is useful for papyrus wetland management strategies, it is recognized that the study period was too short to permit a generalized recommendation.

The objective of this study was to survey and document pesticide residue levels in the lower Nyando ⁄ Sondu-Miriu catchment areas of Lake Victoria, Kenya, during the dry and rainy seasons of 2009. Water and sediment samples from the Nyando ⁄ Sondu-Miriu Basin were analysed for selected pesticide residues, using gas chromatography equipped with Ni 63 and CP-SIL 8CB-15m and TSD detectors for organochlorine and organophosphorus pesticide residues, respectively. The findings indicated that banned organochlorines are still being used in the catchment. Dieldrin and p,p¢-DDD were notably higher (P < 0.05) in concentrations than their metabolically formed analogues of aldrin and DDT, respectively. Notably, organophosphorus was below detection levels in water samples, whereas diazinon and malathion were at higher levels in sediment samples. The total residues of DDT, HCH, methoxychlor and endrin generally were below WHO drinking water limits of 2, 2, 20 and 0.01 lg L )1 , respectively, whereas aldrin and dieldrin were above the recommended values of 0.03 lg L )1 . Agricultural activities in the Lake Victoria Basin are influencing accumulation of the pesticide residues in the basin rivers and the lake. The study recommends creation of buffer zones around the natural water bodies to reduce the inflow of pesticides into water bodies. An integrated pest management approach that encourages reduced usage of chemical compounds also should be encouraged.

The Lake Victoria Basin (LVB) is a global hotspot of aquatic biodiversity, but aquatic ecosystems are under threat from multiple stressors. Most studies on fish have focused on Lake Victoria, while patterns of fish diversity, distribution, and assemblage structure in influent rivers remain poorly understood. To assess threats and conservation status of riverine fishes, we used sampling surveys and searches of published and gray literature to compile data on diversity, distribution, and abundance. In total, 72 fish species were found to inhabit Kenyan rivers and associated wetlands and lakes (excluding Lake Victoria). Low‐order streams (first to third order) in headwaters of rivers are species‐poor and dominated by small‐bodied cyprinids (Enteromius spp.) and clariids (Clarias spp.). A small number of fishes are endemic to rivers, and species turnover across river basins is low. Species dominance is high, with 10 species accounting for >90% of all individuals and weights. Two cyprinid species (Labeobarbus altianalis and Labeo victorianus) account for >65% of all individuals and weights (biomass) per unit effort. Most species occur in small numbers and low biomass is insufficient to sustain a commercial riverine fishery. A review of the literature continues to indicate a reduction in migratory runs of potamodromous fishes from Lake Victoria into influent rivers, although some species, such as L. victorianus and L. altianalis, also maintain stenotopic populations in rivers. Most of the exotic fishes introduced in Lake Victoria, such as Oreochromis nilotics, Oreochromis, Coptodon zillii, Coptodon rendalli, and Gambusia affinis, have invaded and established themselves in rivers, thereby posing a threat to riverine populations. Although this study focuses on Kenyan rivers, the distribution patterns of fishes reflect other rivers of the LVB and have broad implications on threats to riverine biodiversity in other regions undergoing development around the world.

No abstract